Some time in 2006, while listening to the Gavotte from J. S. Bach's
Orchestral Suite No. 4 in D, It occurred to me that much of what I was hearing
was, in essence, the music of Mendelssohn's popular carol, Hark! The Herald Angels Sing.

We know that Mendelssohn was an admirer and promoter of Bach's music. And it struck me that the melodic
and harmonic similarities between the Gavotte and the carol are surely too great to be coincidental.
It seems to me that Mendelssohn has adapted Bach's music for this carol.

But was this already a known and not particularly remarkable fact? From the responses I have had since,
it would seem not.

I took the liberty of emailing noted Australian musician and host of ABC Classic FM's Keys to Music program, Graham Abbott, who very kindly wrote back:

Thanks for your fascinating email. This is the first I have heard of such a connection. I must confess I hadn't noticed the similarities
before but I must admit there is a certain similarity in the melodic and harmonic direction of the music. I wouldn't like to say that Mendelssohn was consciously utilising Bach's melody, but who knows what music from his subconscious seeped into his writing of the carol?

In any case, having made this discovery, I thought it would be an interesting exercise
to create an "original Bach version" of Hark! The Herald by setting the
words of the carol to the music of Bach's Gavotte, in an arrangement for choir and keyboard.

Bach's Christmas Carol is the result. You can download it from here in these formats:

Other than dropping the key from D to G major in order to fit the vocal range,
I have kept Bach's original music effectively intact, redistributing the notes of his orchestral setting
among the four voices and accompaniment, and only joining or splitting certain notes when necessary to
fit the words. The four-bar introduction (which does not occur in the Orchestral Suite) is taken from the
transitional passage eight bars before the end.